A topic much discussed at the present time is the idea of expanding the bandwidth for acoustic signals, e.g. expanding from 4 kHz telephony bandwidth to 8 kHz broadband telephony, since this will be accompanied by a significant improvement in the quality of the voice signal.
However, bandwidth is a limited resource, in particular in mobile cellular communications, in which at least a part of the transmission takes place over a radio link. That is to say that the predefined, limited bandwidth has to be distributed among a plurality of users. If the bandwidth is then increased for one user, it necessarily follows, assuming the number of users remains the same, that the bandwidth available to the remaining users will be reduced.